This is probably because of a bug I already posted on the tracker (here
For one of my games I have some kind of workaround, which works best with vertical platforms, not so much with horizontal I'm afraid. Still it's better than the constant vibrating. Since it's tailored for my own scrolling system, it's kind of hard to give you actual events for the mentioned workaround. If you want some pointers though, feel free to contact me via PM.
There's a good chance this might get fixed in the upcoming release, so keep your fingers crossed.